The present invention relates to an apparatus for measuring the degree of leakage from a fluid pressure passageway. The invention may be utilized in fuel injection systems for automotive engines, air conditioning systems, hydraulic power systems and the like.
It has been known in the art to measure the leakage from, for example, a high pressure supply line for an engine fuel injection system using a Bourdon tube apparatus. A fluid pressure source is connected to the line after which time the line is isolated by means of a valve. The time required for the pressure in the line to drop from one value to a lower value is measured. This value corresponds to the degree of leakage. The greater the degree of leakage, the shorter the length of time required for the line pressure to drop from a high value to a lower value.
This method of measuring the amount of leakage cannot be considered entirely satisfactory. Generally, a Bourdon tube apparatus provides an unstable indication and is extremely sensitive to temperature variations which change the reading. Although it is possible to convert the output of a Bourdon tube to an electrical signal, the electrical components required for such conversion are also sensitive to temperature variations.
Probably the most serious drawback of the prior art system is that the method is basically inaccurate and the results vary considerably depending on the person taking the measurement. It is also hard to standardize the measurement procedure and properly train personnel to take the measurements.